QgsTransformEffect class

A paint effect which applies transformations (such as move, scale and rotate) to a picture.

Reference

Base classes

class QgsPaintEffect: Base class for visual effects which can be applied to QPicture drawings.

Public static functions

static auto create(const QgsStringMap& map) -> QgsPaintEffect*: Creates a new QgsTransformEffect effect from a properties string map.

Constructors, destructors, conversion operators

QgsTransformEffect() defaulted: Constructor for QgsTransformEffect.

Public functions

auto clone() const -> QgsTransformEffect* override: Duplicates an effect by creating a deep copy of the effect.
auto properties() const -> QgsStringMap override: Returns the properties describing the paint effect encoded in a string format.
void readProperties(const QgsStringMap& props) override: Reads a string map of an effect's properties and restores the effect to the state described by the properties map.
auto reflectX() const -> bool: Returns whether transform will be reflected along the x-axis.
auto reflectY() const -> bool: Returns whether transform will be reflected along the y-axis.
auto rotation() const -> double: Returns the transform rotation, in degrees clockwise.
auto scaleX() const -> double: Returns the x axis scaling factor.
auto scaleY() const -> double: Returns the y axis scaling factor.
void setReflectX(const bool reflectX): Sets whether to reflect along the x-axis.
void setReflectY(const bool reflectY): Sets whether to reflect along the y-axis.
void setRotation(const double rotation): Sets the transform rotation, in degrees clockwise.
void setScaleX(const double scaleX): Sets the x axis scaling factor.
void setScaleY(const double scaleY): Sets the y axis scaling factor.
void setShearX(const double shearX): Sets the x axis shearing factor.
void setShearY(const double shearY): Sets the y axis shearing factor.
void setTranslateMapUnitScale(const QgsMapUnitScale& scale): Sets the map unit scale used for the transform translation.
void setTranslateUnit(const QgsUnitTypes::RenderUnit unit): Sets the units used for the transform translation.
void setTranslateX(const double translateX): Sets the transform x translation.
void setTranslateY(const double translateY): Sets the transform y translation.
auto shearX() const -> double: Returns the x axis shearing factor.
auto shearY() const -> double: Returns the y axis shearing factor.
auto translateMapUnitScale() const -> const QgsMapUnitScale&: Returns the map unit scale used for the transform translation.
auto translateUnit() const -> QgsUnitTypes::RenderUnit: Returns the units used for the transform translation.
auto translateX() const -> double: Returns the transform x translation.
auto translateY() const -> double: Returns the transform y translation.
auto type() const -> QString override: Returns the effect type.

Protected functions

auto boundingRect(const QRectF& rect, const QgsRenderContext& context) const -> QRectF override: Returns the bounding rect required for drawing the effect.
void draw(QgsRenderContext& context) override: Handles drawing of the effect's result on to the specified render context.

Function documentation

static QgsPaintEffect* QgsTransformEffect::create(const QgsStringMap& map)

Creates a new QgsTransformEffect effect from a properties string map.

Parameters
map	encoded properties string map
Returns	new QgsTransformEffect

QgsTransformEffect* QgsTransformEffect::clone() const override

Duplicates an effect by creating a deep copy of the effect.

Returns	clone of paint effect

QgsStringMap QgsTransformEffect::properties() const override

Returns the properties describing the paint effect encoded in a string format.

Returns	string map of properties, in the form property key, value

void QgsTransformEffect::readProperties(const QgsStringMap& props) override

Reads a string map of an effect's properties and restores the effect to the state described by the properties map.

Parameters
props	effect properties encoded in a string map

bool QgsTransformEffect::reflectX() const

Returns whether transform will be reflected along the x-axis.

Returns	true if transform will reflect horizontally

bool QgsTransformEffect::reflectY() const

Returns whether transform will be reflected along the y-axis.

Returns	true if transform will reflect horizontally

double QgsTransformEffect::rotation() const

Returns the transform rotation, in degrees clockwise.

double QgsTransformEffect::scaleX() const

Returns the x axis scaling factor.

Returns	x axis scaling factor, where 1.0 = no scaling

double QgsTransformEffect::scaleY() const

Returns the y axis scaling factor.

Returns	y axis scaling factor, where 1.0 = no scaling

void QgsTransformEffect::setReflectX(const bool reflectX)

Sets whether to reflect along the x-axis.

Parameters
reflectX	true to reflect horizontally

void QgsTransformEffect::setReflectY(const bool reflectY)

Sets whether to reflect along the y-axis.

Parameters
reflectY	true to reflect horizontally

void QgsTransformEffect::setRotation(const double rotation)

Sets the transform rotation, in degrees clockwise.

void QgsTransformEffect::setScaleX(const double scaleX)

Sets the x axis scaling factor.

Parameters
scaleX	factor to scale x axis by, where 1.0 = no scaling

void QgsTransformEffect::setScaleY(const double scaleY)

Sets the y axis scaling factor.

Parameters
scaleY	factor to scale y axis by, where 1.0 = no scaling

void QgsTransformEffect::setShearX(const double shearX)

Sets the x axis shearing factor.

Parameters
shearX	x axis shearing

void QgsTransformEffect::setShearY(const double shearY)

Sets the y axis shearing factor.

Parameters
shearY	y axis shearing

void QgsTransformEffect::setTranslateMapUnitScale(const QgsMapUnitScale& scale)

Sets the map unit scale used for the transform translation.

Parameters
scale	map unit scale for translation

void QgsTransformEffect::setTranslateUnit(const QgsUnitTypes::RenderUnit unit)

Sets the units used for the transform translation.

Parameters
unit	units for translation

void QgsTransformEffect::setTranslateX(const double translateX)

Sets the transform x translation.

Parameters
translateX	distance to translate along the x axis

void QgsTransformEffect::setTranslateY(const double translateY)

Sets the transform y translation.

Parameters
translateY	distance to translate along the y axis

double QgsTransformEffect::shearX() const

Returns the x axis shearing factor.

Returns	x axis shearing

double QgsTransformEffect::shearY() const

Returns the y axis shearing factor.

Returns	y axis shearing

const QgsMapUnitScale& QgsTransformEffect::translateMapUnitScale() const

Returns the map unit scale used for the transform translation.

Returns	map unit scale for translation

QgsUnitTypes::RenderUnit QgsTransformEffect::translateUnit() const

Returns the units used for the transform translation.

Returns	units for translation

double QgsTransformEffect::translateX() const

Returns the transform x translation.

Returns	X distance translated along the x axis

double QgsTransformEffect::translateY() const

Returns the transform y translation.

Returns	Y distance translated along the y axis

QString QgsTransformEffect::type() const override

Returns the effect type.

Returns	unique string representation of the effect type

QRectF QgsTransformEffect::boundingRect(const QRectF& rect, const QgsRenderContext& context) const override protected

Returns the bounding rect required for drawing the effect.

Parameters
rect	original source bounding rect
context	destination render context
Returns	modified bounding rect

This method can be used to expand the bounding rect of a source picture to account for offset or blurring effects.

void QgsTransformEffect::draw(QgsRenderContext& context) override protected

Handles drawing of the effect's result on to the specified render context.

Parameters
context	destination render context

Derived classes must reimplement this method to apply any transformations to the source QPicture and draw the result using the context's painter.